Heart failure (HF) is associated with a skeletal muscle dysfunction, characterized by an increased fatigue that does not correlate with impaired myocardial function and physical inactivity that is commonly associated with HF. We identified in skeletal muscle of HF rats, a dysfunction of type 1 ryanodine receptors (RyR1) similar to that observed on the cardiac channel (RyR2), due to an hyperphosphorylation of the RyR and a dissociation of the regulatory protein FKBP12. This dysfunction, in addition to mitochondrial impairment, contributes in this animal model to the reduced exercise capacity observed during HF. Our goal is to analyse the impact of HF on calcium homeostasis, mitochondrial function and oxidative stress in human skeletal muscle. This project, performed on muscle biopsies, will also allow us to correlate calcium homeostasis and mitochondrial function (before and after exercise training) to circulating factors (cytokines, catecholamines) susceptible to trigger this muscle dysfunction.